The balanced chemical reaction is:
Zn + 2AgNO3 =  Zn(NO3)2 + 2Ag
To determine the amount of the reactant left, we have to determine which is the limiting and the excess reactant. We do as follows:
5.65 g Zn ( 1 mol / 65.38 g) = 0.09 mol Zn
21.6 g AgNO3 (1 mol / 169.87 g) = 0.13 mol AgNO3
The limiting reactant would be silver nitrate since it is consumed completely in the reaction. The excess reactant would be zinc. 
Excess Zinc = 0.09 mol Zn - (0.13 / 2) mol Zn = 0.025 mol Zn left
        
                    
             
        
        
        
Answer is: a) in the presence of a base.
Phenolphthalein is colorless in acidic solutions and pink in basic solutions.
Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations.
Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄). 
When solution turns phenolphthalein pink, it means it is basic (pH>7).
 
        
                    
             
        
        
        
 <span>CO is the limiting reactant 
( 25.0 x 3 = 75 moles of CO are required) 
Moles Fe = 30.0 x 2 / 3 = 20.0 
mass Fe = 20.0 x 55.847 g/mol=1117 g </span><span>
I'm just saying</span>
        
             
        
        
        
I think it’s A but I’m not sure, if it’s wrong I’m sorry
        
             
        
        
        
Answer: The values become more negative
Explanation: I just took the quiz and got it correct :)